1. Field of the Invention
The present invention relates to the cushioning of energy produced by impacts on vehicles and in particular relates to an improved bumper assembly for vehicles, as well as a vehicle comprising this bumper assembly.
2. Related Art and Other Considerations
It is known in the motor vehicle industry that bumpers are provided at the front and at the rear of a vehicle in order to absorb the impact energy and limit as far as possible any injury to passengers or pedestrians who may be involved in the impact, as well as damage to the vehicle parts.
At present, a vehicle, in order to be type-approved, is subject to so-called “crash tests”. These crash tests may be divided up, depending on the type of impact, into different categories. Moreover, there exist different regulations for the same impact category when type-approving a vehicle in Europe or in North America (Canada and the USA). The biggest difference between the regulations exists in the fact that, in order to obtain type-approval in North America, the vehicle must pass tests at a higher speed than the speed stipulated by the European regulations (generally substantially twice said speed). The speed of the longitudinal impact test stipulated in paragraph 2.7 of the standards for vehicle type-approval in Europe [“Agreement concerning the adoption of uniform conditions of approval and reciprocal recognition of approval for motor vehicle equipment and parts”, reached in Geneva on 20 Mar. 1958, Addendum 41, Regulation No. 42, “Uniform provisions concerning the approval of vehicles with regard to their front and rear protective devices”], referred to below in short as “ECE 42”, is 4 km/h. The corresponding test speed stipulated by the Regulations TP-581-01 (25 Apr. 1990) issued by the U.S. Department of Transportation National Highway Traffic Safety Administration” (for type-approval in the USA) or that envisaged for type-approval in Canada by Standard 215 of the Motor Vehicle Safety Act, Motor Vehicle Safety Regulations”, is about 8 km/h.
Many vehicle manufacturers design and construct vehicles both for the European market and for the North American market.
If a vehicle is originally designed for the European market, the manufacturer envisages a bumper assembly which is able to satisfy the abovementioned European standard. However, it is highly probable that this bumper assembly will not be sufficient for the vehicle to pass successfully the crash tests envisaged by the North American standards. The manufacturer must therefore make certain adaptations. These adaptations usually consist in increasing the thickness of the layer of cushioning material. In this way, the bumper assembly protrudes by a greater amount from the shape of the vehicle and modifies the dimensions, the aerodynamics and the aesthetic appearance thereof. If the manufacturer is unable (or does not wish) to modify the shape of the vehicle, the cross member to which the layer of cushioning material is fastened must be greatly reinforced (i.e. the same cross member may not be mounted).
If, on the other hand, a vehicle is originally designed for the North American market, the manufacturer envisages a bumper assembly suitable for complying with the abovementioned North American standard. This bumper assembly will project greatly from the shape of the vehicle since it will have a fairly thick layer of cushioning material. This results in an unacceptable increase in the dimensions of the vehicle, negative aerodynamic characteristics and, very often, an unattractive aesthetic appearance when marketing the vehicle in the European market.
EP 0 323 038 A (LADNEY, MICHAEL, JR) discloses a vehicle bumper structure having a body secured to the vehicle and a resiliently deformable fascia spaced forwardly of the bumper structure. The volume defined therebetween is filled with an integral skin urethane foam that is resiliently deformable and integrally bonded to both members. The body includes a beam having an upper flange and a lower flange. The fascia is connected to the body at the upper flange thereof but it is not secured to the column rails of the vehicle. The fascia mainly has aesthetic purposes and can act against very small entity crashes. The arrangement of EP 0 323 038 A is unable to be adapted so as to allow compliance with various regulations without an increase in the length of the vehicles.
EP 1 504 966 A (ADLEV S. R. L.) discloses a bumper assembly for a vehicle comprising: at least two crash boxes; a cross member made of a first plastic material which, during use, extends over a distance at least corresponding to that between the crash boxes; and at least two substantially indeformable connecting devices connected to said cross member for rigidly fixing said cross member to a vehicle chassis, wherein said at least two substantially indeformable connecting devices are connected to the cross member at positions corresponding to the crash boxes. A bumper shield or fascia is also provided for aesthetic purposes. Typically, the bumper shield is connected to the body shell of the vehicle. When it crashes against an obstacle, it gets deformed and transmits such deformation to the body shell of the vehicle. The arrangement of EP 1 504 966 A is unable to be adapted so as to allow compliance with various regulations without an increase in the length of the vehicles.
EP 0 425 923 A (BASF AKTIENGESELLSCHAFT) discloses a recyclable polypropylene-based bumper system comprising a bumper support comprising glass fibre-reinforced polypropylene, an energy-absorbing foam core comprising foamed polypropylene, and a tough shell which comprises EP rubber-modified polypropylene and may, if desired, be painted. The bumper system can be recycled by mechanical comminution, extrusion and granulation. The granules can be used to produce injection mouldings having good mechanical properties. The bumper system of EP 0 425 923 A corresponds to a single cross member (bumper support) and fascia (shell) arrangement with foam therebetween. The bumper support is connected to the shell at upper and lower flanges of the bumper support. The arrangement of EP 0 425 923 A is unable to be adapted so as to allow compliance with various regulations without an increase in the length of the vehicles.
US 2004/145195 A1 (MOOIJMAN FRANK ET AL) discloses a bumper assembly for an automotive vehicle. In an example embodiment, the assembly comprises a beam and an injection molded energy absorber secured to the beam. The energy absorber comprises at least one crash can. The assembly further comprises a fascia for covering the beam and the energy absorber. The fascia seems to be configured for being connected to the body shell of the vehicle. The arrangement of US 2004/145195 A1 is unable to be adapted so as to allow compliance with various regulations without an increase in the length of the vehicles.
U.S. Pat. No. 4,762,352 A (ENOMOTO ET AL) discloses a bumper for a motorcar having a shock absorbing member made of a foamed synthetic resin attached to a front surface of a backup beam connected to left and right stays of a car body. The resultant assembly of those members is covered at its front, upper and lower surfaces with a synthetic resin facing member which is nearly in the form of a channel in section. The backup beam is formed out of fiber-reinforced synthetic resin and is a hollow beam member having depth which is comparatively large at its middle portion extending between the two stays and is comparatively small at its both end portions extending from the two stay connecting portions thereof to the terminal ends thereof. The shock absorbing member is formed so that the change in the depth thereof is in inverse relation to the foregoing change in the depth of the backup beam so that the depth of the entire resultant assembly may nearly constant. The backup beam can be made of a channel-shaped front shell member and a channel-shaped rear shell member which are joined together at their flanges to be formed into a hollow beam. The facing member is connected to rear shell member at a facing member attaching edge. The arrangement of U.S. Pat. No. 4,762,352 A is unable to be adapted so as to allow compliance with various regulations without an increase in the length of the vehicles.